1. Field of the Invention
The present invention relates to a semiconductor device having a circuit constructed of a thin film transistor (hereinafter referred to as TFT), and to a method of manufacturing the same. For example, the present invention relates to an electro-optical device, which is represented by a liquid crystal display device, and to electronic equipment loaded with the electro-optical device (electric device) as a part.
Note that, in this specification, the term semiconductor device indicates general devices that function by utilizing semiconductor characteristics, and that electro-optical devices, semiconductor devices, and semiconductor circuits are all included in the category of the semiconductor device.
2. Description of the Related Art
In recent year, a technique for constructing a thin film transistor (hereinafter referred to as TFT) using a semiconductor thin film (on the order of several to several hundreds nm in thickness) formed on the substrate having an insulating surface is attracting an attention. The TFTs are widely used for electronic devices such as an IC or an electro-optical device, and the development of a switching element for a liquid crystal display device is particularly urgent.
In the liquid crystal devices, an attention is paid on an active matrix liquid crystal display device in which, to obtain an image with high quality, pixel electrodes are arranged in matrix and the TFT is used as a switching element for connecting the respective pixel electrodes.
The active matrix liquid crystal display devices are roughly classified into two types. There are known a transmission type and a reflection type active matrix liquid crystal display devices.
In particular, the reflection type liquid crystal display device does not use a back light, thereby having a merit in that a power consumption is small, as compared with the transmission type liquid crystal display device. Therefore, there is a great demand as a direct vision type display for a mobile computer or a video camera.
Note that the reflection type liquid crystal display device has a mechanism of displaying an image using an optical modulation action of the liquid crystal, in which a selection is made from a state where an incident light is reflected on a pixel electrode to be outputted outside the device or a state where the incident light is not outputted outside the device, and the display of bright and dark is performed, and further those are combined. The pixel electrode of the reflection type liquid crystal display device is generally made from a metallic material having high reflectivity, such as aluminum, and is electrically connected to a switching element such as a thin film transistor.
Further, in the liquid crystal display device, TFTs having semiconductors made of amorphous silicon or poly silicon, are arranged in matrix, and a liquid crystal material is sandwiched between a device electrode on which a pixel electrode connected to each TFT, a source wiring and a gate wiring each are formed and an opposing substrate having an opposing electrode arranged oppositely thereto. Besides, a color filter for displaying colors is stuck on the opposing substrate, and polarization plates are arranged on the device substrate and the opposing substrate, respectively, as optical shutters, to perform the color display.
These color filters have colored layers consisting of R (red), G (green), and B (blue), a light shielding mask for covering only gaps between pixels, and extracting a red color, a green color and a blue color by transmitting light therethrough. Further, the light shielding mask is generally constructed of an organic film containing a metallic film (chromium etc.) or a black pigment. These color filters are arranged at positions corresponding to the pixel, thereby being capable of changing the color to be extracted for each pixel. Note that the position corresponding to the pixel means the position that accords with the pixel electrode.
In the conventional liquid crystal display device in which a metallic film is used as the light shielding mask of the color filter, there arose a problem in that a parasitic capacitor is generated with the other wiring to easily cause a delay in signal. Besides, in the case an organic film containing a black pigment is used as the light shielding mask of the color filter, there arose a problem in the number of manufacturing steps increases.
An object of the present invention is to provide a pixel structure capable of shielding between TFT and pixel from light without using a light shielding mask (black matrix). The present invention has a feature in that, as one of means for shielding light, a lamination film consisting of two colored layers (lamination film consisting of a red-colored layer and a blue-colored layer or a lamination film consisting of a red-colored layer and a green-colored layer) is formed on an opposing substrate as a light shielding portion so as to overlap with a TFT formed on a device electrode.
In this specification, a xe2x80x9cred-colored layerxe2x80x9d is a layer which absorbs a part of light irradiated onto a colored layer to extract a red color therefrom. Further, similarly, a xe2x80x9cblue-colored layerxe2x80x9d is a layer which absorbs a part of light irradiated onto a colored layer to extract a blue color therefrom, and a xe2x80x9cgreen colorxe2x80x9d is a layer which absorbs a part of light irradiated onto a colored layer to extract a green color therefrom.
The structure of the present invention disclosed in this specification relates to an electro-optical device, characterized by comprising: a first light shielding portion including a lamination of a first colored layer and a second colored layer; and a second light shielding portion including a lamination of the first colored layer and a third colored layer.
The structure of the present invention disclosed in this specification relates to an electro-optical device, characterized by comprising: at least a thin film transistor; a first light shielding portion including a lamination of a first colored layer and a second colored layer; and a second light shielding portion including a lamination of the first colored layer and a third colored layer, wherein the first and second light shielding portions overlap at least a channel region of the thin film transistor.
Further, another structure of the present invention relates to an electro-optical device, characterized in that: the device comprises: a plurality of pixel electrodes; a first light shielding portion including a lamination of a first colored layer and a second colored layer; and a second light shielding portion including a lamination of the first colored layer and a third colored layer, and that: the first light shielding portion and the second light shielding portion are formed between an arbitrary number of the pixel electrodes and the adjacent pixel electrodes, while overlapping with each other.
Still further, in the above-mentioned respective structures, the device is characterized in that an amount of reflection light of the first light shielding portion and an amount of reflection light of the second light shielding portion are different from each other.
Yet further, in the above-mentioned respective structures, the device is characterized in that the first colored layer is a red color. Also, the second colored layer is a blue color. Further, the third colored layer is a green color.
Moreover, in the above-mentioned respective structures, the device is characterized in that the third colored layer has a stripe shape.
Furthermore, in the above-mentioned respective structures, the device is characterized in that the first light shielding portion and the second light shielding portion are formed on an opposing substrate.
In addition, in the above-mentioned respective structures, the device is characterized in that the electro-optical device is a reflection type liquid crystal display device in which the pixel electrode is a film containing as a main component Al or Ag, or a lamination film thereof.